Electronic counter using multi-position magnetron beam switching tubes



' Jan. 4, 1966 D. GLASER ELECTRONIC COUNTER USING MULTI-POSITION MAGNETRON BEAM SWITCHING TUBES Filed Sept. 8, 1961 mudaow mw sm INVENTOR.

DA V/D GLA SE R A TTORNE Y A an prising one counting stage of the counter.

United States Patent 3,227,918 ELECTRONIC COUNTER USING MULTI-POSI- TION MAGNETRON BEAM SWITCHING TUBES David Glaser, Greenbrook, N.J., assignor to Burroughs Corporation, Detroit, Mich., a corporation of Michigan Filed Sept. 8, 1961, Ser. No. 136,937 8 Claims. (Cl. 315-85) This invention relates to electronic counters and particularly to electronic counters using a plurality of multiposition magnetron beam switching tubes connected in cascade.

A multi-position magnetron beam switching tube includes a central electron-emitting cathode and ten groups of electrodes surrounding the cathode, each of which comprises a position to which an electron beam can flow and from which an output signal can be obtained. Each group of electrodes includes a target or output electrode from which the output signal is obtained, a spade electrode which forms and holds an electron beam on its associated spade electrode, and a switching electrode which serves to switch an electron beam from one position to the next. Means are included for providing a longitudinal magnetic field in the tube which combines with electric fields therein to control the movement of an electron beam.

In one mode of operation of a beam switching tube as a counter, all of the switching electrodes are connected together and to a single source of driving pulses. This is known as single-ended drive and presents a problem situation which is solved by the present invention. The problem arises from the fact that a specially shaped pulse of proper time duration is required so that, when it is applied to the commonly connected switching electrodes, it will cause a beam to switch by only one position. Thus, a single applied pulse should cause only one count to be registered in a tube.

In the past, in single-ended drive circuit arrangements, it has not been feasible to directly couple one beam switching tube to another and drive the second substantially directly with a pulse derived from the first. This arrangement has not been feasible because the first tube could not by itself provide the proper pulse to insure that the second tube register only one count for each carry pulse transmitted from the first tube. Thus, auxiliary active circuit elements such as tubes, transistors, magnetic cores or the like were required to provide the required pulses. The elimination of such a requirement would be both functionally and economically desirable.

Another problem arises in a cascade counter using multi-position magnetron beam switching tubes when it is desired to clear and reset an electron beam to the position in a tube from which a carry pulse is transmitted to the next tube. In such a situation, it is necessary to prevent the reset pulse, or any pulse generated by the reset operation, from being transmitted to the next stage and causing a spurious count to be registered.

Accordingly, the objects of the present invention concern the provision of an improved counter circuit using a plurality of multi-position magnetron beam switching tubes directly coupled in cascade without active circuit elements between tubes, which each tube performing counting, carry, and reset operations efficiently and independently.

Briefly, a cascade counter according to the invention includes a plurality of multi-position magnetron beam switching tubes connected in cascade, with each tube com- Each tube includes a plurality of groups of electrodes, each group including at least a target electrode, a spade electrode, and a switching electrode. In each tube, the switching 3,227,918 Patented Jan. 4, 1966 electrodes are connected in two sets with alternate electrodes in each set, and means are provided for periodically changing the DC. bias level of each set of switching electrodes. The periodicity of the change is related to the switching of an electron beam from position to position in the tube. The change in DC potential of the switching electrodes, in eiiect, pre-biases each set of switching electrodes so that a single switching pulse applied to both sets of electrodes causes only one set to switch an electron beam. This arrangement of the switching electrodes is employed both with the first tube in the counting chain, which is driven by an external pulse source, and each successive tube, which is driven directly by the tube which precedes it.

The cascade counter also includes a circuit for clearing and resetting each beam switching tube. This circuit may be used to clear and reset all of the tubes in the counter, or each stage may be provided with its own clear and reset circuit. According to the invention, the clear and reset circuit is coupled to the position in a beam switching tube from which a carry pulse is transmitted to the next tube. Since the reset pulse is generally similar to the carry pulse, means are provided for allowing only the carry pulse to be transmitted as a useful pulse to a successive tube.

The invention is described in greater detail by reference to the single figure of the drawing which is a schematic representation of a circuit embodying the invention.

The principles of the invention are applicable to count ing circuits and particularly to cascade counters using multi-position magnetron beam switching tubes as the individual counting units or counting stages. Magnetron beam switching tubes include the type 6700 tube and tubes known as BEAM-X switches which are manufactured by Burroughs Corporation.

A typical beam switching tube 10 of the type known as a BEAM-X switch is shown in the drawing. This tube is cylindrical in actual construction but is shown schematically in linear form. The tube 10 includes an evacuated envelope 12 which contains a central cathode 14 and ten groups of electrodes spaced radially equidistantly from, and surrounding, the cathode. For convenience, the ten groups of electrodes are numbered consecutively from 1 to 0, and, in the following description of the invention, an electrode may be referred to by the same number as the group of electrodes to hich it belon s.

W Each group of electrodes in tube 10 includes a spade electrode 16, a target electrode 18, an auxiliary shield electrode 19, and a switching electrode Zii, In each group of electrodes, the spade electrode serves to form and hold an electron beam on its associated target electrode which itself receives the greater portion of the electron beam and provides an output signal therefrom. The switching electrode 20, known as a switching grid, is used for switching an electron beam from position to position, and the auxiliary electrode 19 facilitates the switching operation.

The tube 10 also includes suitable means for providing an axial magnetic field which combines with electric fields therein to control the movement of an electron beam. Such means may be an external or internal permanent magnet arrangement (not shown), or some of the electrodes themselves may be permanent magnets.

With respect to the circuit connections of tube 10, the cathode 14 is coupled to a pulse source 24 for generating generally sawtooth waves 26. The waves 26 are used to clear and reset an electron beam in tube 10 and are shaped to have a positive leading portion and gently sloping trailing edge for a purpose to be described below. A phan- 3 tastron circuit or the like may be used to provide these waves.

The targets 18, which are the output electrodes of tube 10, may be utilized in any suitable fashion. For example, they may be connected directly to the glow cathodes of a type 6844A indicator tube, or they may be connected to a printing mechanism or to any other suitable utilization device.

The switching electrodes 20 are connected in two sets, with the electrodes at the odd-numbered positions in one set and the electrodes at the even-numbered positions in the other set. The sets of switching electrodes are both coupled through capacitors 88 and 92 to a suitable source 94 of negative switching or driving pulses 96. These pulses are generally square waves. The auxiliary electrodes 19 are connected together and through a suitable bias resistor 100 to a positive D.C. power supply Vs.

According to the invention, the spade electrodes 16 are connected in two sets, with the even-numbered spades in one set and the odd-numbered spades in the other set. The even-numbered spades are coupled through suitable load resistors 102 to a bus 106 which is connected in turn through a common resistor 108 to a common spade bus 112. The common spade bus 112 is connected at one end to ground and at the other end through a resistor 116 to power source Vs. The even spade bus 106 is also coupled through a resistor 116 to the even-numbered switching electrodes. The odd-numbered spades are similarly coupled through load resistors 102 to an odd spade bus 120 which is connected through a common resistor 124 to the common spade bus 112. The oddnumbered spade bus 120 is also coupled through a resistor 128 to the odd-numbered switching electrodes. Each of the spades, except the spade, is also connected through a capacitor 130 to ground. The 0 spade includes other similar capacitors described below.

The 0 position is the position at which an electron beam is reset after the tube has been cleared, and it is also the position from which a carry pulse 130 is transmitted substantially directly to the next tube 10 in the counting chain. According to the invention, the 0 spade electrode, that is, the spade at the 0 position, is used to perform these two operations. Circuit connections made to the 0 spade for carrying out these operations include a diode 132, the anode of which is connected to the 0 spade and the cathode of which is connected (1) through a capacitor 136 to the cathode 14 and thus to pulse source 24, and (2) through a resistor 138 to the common spade bus 112. The O spade is also coupled through two lines 142 and 146 and coupling capacitors 88' and 92 to the odd and even switching grids of beam switching tube 10 which, it is assumed, is coupled to tube 10 and comprises the next stage of the counting chain. Only portions of the next counting tube 10 are shown, but it is assumed that the tube 10' is the same as tube 10 and includes the same circuit connections where appropriate. The counting chain may include any number of such tubes. Thus, for example, capacitor 88 is coupled the both the odd-numbered switching electrodes and through resistor 128' and the various other spade resistors to the odd-numbered spades. Capacitor 92' is similarly coupled to the even-numbered switching grids and the even-numbered spades.

The network including capacitor 88 and resistor 116' and the network including capacitor 92' and resistor 128' comprise differentiating circuits which receive both carry pulses from the 0 spade of tube 10 and reset pulses from source 24. The difierentiating circuits are designed so that, when a carry pulse, which is approximately a negative square wave similar to pulse 97, is received, they produce a negative pulse of suitable amplitude to cause a beam to switch when this negative pulse is applied to the switching electrodes of the next tube in the counting chain. However, when a reset pulse 26 is applied to the difierentiating circuits, the gently sloping trailing edge passes through and appears as a wave which has too small an amplitude to cause switching of an electron beam in the second tube. 9

These circuit elements connected to the 0 spade also prevent input pulses from source 94 from affecting the 0 spade by performing a suitable filtering action. The capacitors 130 coupled to each of the other spades perform the same function. The various spade resistors and capacitors and the ditferentiating circuits also prevent pulses from source 94 from flowing over the spade buses 106 and and acting as carrier pulses for the next tube 10.

In operation of the circuit of the invention, it is assumed that an electron beam is set at the 0 position in each tube of the counting chain and input counting pulses are applied to the first tube 10 which is thus caused to execute a counting operation. An output pulse is transmitted by a target electrode each time a beam switches into a position in each tube. In tube 10, an electron beam is switched from position to position by the application of negative switching pulses 96 from the source 94 to both sets of switching grid electrodes 20. However, only one set of switching electrodes is properly energized, that is, carries the proper D.C. bias to cause switching. The D.C. bias levels of the two sets of switching grids are set by the potentials of the spade buses 106 and 120, and these optentials are determined by the voltage drops across the resistors 108 and 124. When a beam is at, for example, an even position, some of the beam current flows through the spade at this even position and produces a voltage drop across resistor 108. Thus, spade bus 106 is at a lower D.C. potential than spade bus 120, and the even switching grids are at a lower potential than the odd grids. The input pulse 96 applied to the switching grids is of such a magnitude that, when combined with the D.C. potentials on the grids, lowers only the set of even grids, including the grid at the position receiving the beam, sufiiciently to cause the beam to switch to the next position, an odd-numbered position. At this time, when the beam leaves the even-numbered position, the even spade bus 106 rises to a more positive D.C. level, and the spade current in the odd position causes the D.C. level of the odd spade bus 120 to be lowered in the manner described above. Thus, an odd-numbered switching electrode is now properly biased to cause beam switching when the next pulse 96 is applied. Each input pulse 96 thus causes an electron beam to switch by one position, with an output pulse being generated by the target electrode at each position.

When an electron beam flows into the 0 position to indicate the end of a counting cycle, a carry pulse is generated and transmitted to tube 10' to register a count therein. The carry pulse is generated by current flow through the 0 spade and then through the 0 spade load resistor 102, across which the carry pulse is generated as a negative generally square wave. This carry pulse is coupled through the differentiating circuits to the switching electrodes of tube 10. It is assumed that an electron beam is flowing to the 0 position in tube 10' and the switching electrodes 20' are at dilferent D.C. levels, with the even-numbered grid at the lower level. Thus, the carry pulse, when applied to the switching electrodes, suitably combines with the lower D.C. level of the 0 grid to cause the electron beam in tube 10' to switch by one position and thus register a count therein. The tube 10 then executes another counting cycle, at the end of which another carry pulse is transmitted to tube 10, and another count is registered therein.

In operation of the clear and reset portion of the invention, assuming that an electron beam is at the 9 position, which is assumed to be the next to last position of a counting cycle, at this time a pulse 26 is applied to the cathode 14 from source 24. The leading portion of pulse 26 raises the cathode 14 to a sufficiently positive potential to cause an electron beam to clear in tube 10. The trailing negative portion is coupled through capacitor 136 and diode 132 to the 0 spade which is lowered sufficiently in potential to cause an electron beam to form at the position. However, the differentiating circuits lying between the 0 spade of tube 10 and the switching electrodes of tube 10' change the reset pulse to a low amplitude wave which is unable to cause the switching electrodes 20 in tube 10' to perform a switching operation. The pulse source 24 may also be coupled to counting tube 10 and any other tubes which may be in the counting chain to cause them to perform the same clear and reset operation. Separate clear and reset circuits may also be provided for each tube.

The present invention provides a cascade counter using multi-position magnetron beam switching tubes in which a plurality of separate and independent functions are performed without one interfering with another. Thus, each counting tube can execute a counting cycle and obtain an output signal from the target electrode at each position in the tube. In addition, both the target and spade at a selected position in each tube can be used to provide both a useful output signal and a separate useful carry pulse. The last-mentioned spade electrode can also be used to reset an electron beam without interfering with any of its other functions.

An important advantage of the invention is that a simple and direct arrangement is provided for coupling a carry pulse from one tube to the next tube without active circuit elements such as tubes or transistors being required.

What is claimed is:

1. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes, each of which comprises a position to which an electron beam may flow;

each group including a target electrode which receives an electron beam and produces an output signal therefrom, a spade electrode which holds an electron beam on its associated target electrode, and a switching electrode which serves to switch an electron beam from one group of electrodes to the next;

said spade electrodes being connected in two sets with alternate spades being in the same set;

said switching electrodes being connected in two sets with alternate electrodes being in the same set; each set of spades being electrically connected to the corresponding set of switching electrodes so that the spade at any one position is connected to the switching electrode at that position whereby current flow through any one spade is reflected as a change in potential of the associated switching electrode; this change in potential of a switching electrode representing a pre-bias condition for the switching operation;

and a single source of switching pulses coupled to both sets of switching electrodes, the pre-bias potential of a switching electrode combining with a switching pulse from said single source to cause an electron beam to switch from one position to the next.

2. The circuit defined in claim 1 wherein each set of spade electrodes is coupled to a common load resistor whereby current flow through a spade electrode produces a potential across its common load resistor, said potential producing the pre-bias condition of the associated switching electrode.

3. The counter defined in claim 1 wherein a selected spade electrode serves both to reset an electron beam in the tube and to transmit .a carry pulse to the next tube in the counting chain,

and a differentiating circuit coupled to said selected spade electrode, said differentiating circuit being adapted to provide a switching pulse when a carry pulse is applied thereto,

said differentiating circuit also being adapted to modify a reset pulse which is applied thereto so that the resulting waveform is not usable as a switching pulse.

4. the counter defined in claim 1 wherein a selected spade electrode serves both to reset an electron beam and to transmit a carry pulse to the next tube in the counting chain,

a differentiating circuit coupled to said selected spade electnode,

said differentiating circuit being adapted to provide a switching pulse when a carry pulse is applied thereto,

and a source of clear and reset pulses coupled to the cathode of said tube and to said selected spade electrode,

said differentiating circuit also being adapted to modify a reset pulse so that the resulting waveform is not usable as a switching pulse.

5. The counter defined in claim 1 wherein a selected spade electrode serves both to reset an electron beam and to transmit a carry pulse to the next tube in the counting chain,

a second magnetron beam switching tube having the same electrodes as said first-mentioned magnetron beam switching tube,

a differentiating circuit coupled between said selected spade electrode and the switching electrodes of said second tube,

said differentiating circuit being adapted to provide a usable switching pulse when a carry pulse is applied thereto,

and a source of clear and reset pulses coupled to the cathode of the first-mentioned tube and to said selected spade electrode,

said differentiating circuit also being adapted to modify a reset pulse so that the resulting waveform is not usable as a switching pulse.

6. The counter defined in claim 1 wherein a selected spade electrode serves both to reset an electron beam and to transmit a carry pulse to the next tube in the counting chain,

a second magnetron beam switching tube having the same electrodes as said first-mentioned magnetron beam switching tube,

the switching electrodes and the spade electrodes of said second tube being connected in two sets as in the first tube,

a differentiating circuit coupled between said selected spade electrode and each set of switching electrodes of said second tube,

said differentiating circuits being adapted to provide a usable switching pulse for said switching electrodes of said second tube when a carry pulse is applied thereto from said selected spade of said first tube,

and a source of clear and reset pulses coupled to the cathode of the first-mentioned tube and to said selected spade electrode,

said differentiating circuits also being adapted to modify a reset pulse applied thereto from said selected spade so that the resulting waveform is not usable as a switching pulse when applied to said switching electrodes of said second tube.

7. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes, each of which comprises a position to which an electron beam may flow;

each group including a target electrode which receives an electron beam and produces an output signal therefrom, a spade electrode which holds an electron beam on its associated target electrode, and a switching electrode which serves to switch an electron beam from one group of electrodes to the next;

said spade electrodes being connected in two sets with alternate electrodes in each set;

said switching electrodes being connected in two sets with alternate electrodes in each set;

each set of spade electrodes having a common impedance through which spade current flows when an electron beam flows to a tube position;

means coupling each set ofspade electrodes to the corresponding 'set of switching electrodes which are at thesame positions'as the .spadeelectrodes'so'that a spade electrode at any position is coupled to'the switching electrode at the same position;

whereby the potential of each set of switching electrodes is affected by current flow through aspade electrode when an electron beamflows to a position in said tube;

and a single source of negative switching pulses coupled to both sets of switching electrodes;

each switching pulse causing a switchingoperation' to be performed only by the set of switching electrodes which is associated with a spade-electrode which is References Cited by the Examiner UNITED STATES PATENTS 2,827,590 3/1958 Bethke 3l5--816 2,857,552 10/1958 .Hobe'rg 3158.6 X 2,871,399 1/1959 Scuitto 3158.6

GEORGE N. WESTBY, Primary Examiner.

RALPH G. NILSON, Examiner. 

1. A COUNTER CIRCUIT INCLUDING A MAGNETRON BEAM SWITCHING TUBE HAVING A CATHODE AND A PLURALITY OF GROUPS OF ELECTRODES, EACH OF WHICH COMPRISES A POSITION TO WHICH AN ELECTRON BEAM MAY FLOW; EACH GROUP INCLUDING A TARGET ELECTRODE WHICH RECEIVES AN ELECTRON BEAM AND PRODUCES AN OUTPUT SIGNAL THEREFROM, A SPADE ELECTRODE WHICH HOLDS AN ELECTRON BEAM ON ITS ASSOCIATED TARGET ELECTRODE, AND A SWITCHING ELECTRODE WHICH SERVES TO SWITCH AN ELECTRON BEAM FROM ONE GROUP OF ELECTRODES TO THE NEXT; SAID SPADE ELECTRODES BEING CONNECTED IN TWO SETS WITH ALTERNATE SPADES BEING IN THE SAME SET; SAID SWITCHING ELECTRODES BEING CONNECTED IN TWO SETS WITH ALTERNATE ELECTRODES BEING IN THE SAME SET; EACH SET OF SPADES BEING ELECTRICALLY CONNECTED TO THE CORRESPONDING SET OF SWITCHING ELECTRODES SO THAT THE SPADE AT ANY ONE POSITION IS CONNECTED TO THE SWITCHING ELECTRODE AT THAT POSITION WHEREBY CURRENT FLOW THROUGH ANY ONE SPADE IS REFLECTED AS A CHANGE IN POTENTIAL OF THE ASSOCIATED SWITCHING ELECTRODE; THIS CHANGE IN POTENTIAL OF A SWITCHING ELECTRODE REPRESENTING A PRE-BIAS CONDITION FOR THE SWITCHING OPERATION; AND A SINGLE SOURCE OF SWITCHING PULSES COUPLED TO BOTH SETS OF SWITCHING ELECTRODES, THE PRE-BIAS POTENTIAL OF A SWITCHING ELECTRODE COMBINING WITH A SWITCHING PULSE FROM SAID SINGLE SOURCE TO CAUSE AN ELECTRON BEAM TO SWITCH FROM ONE POSITION TO THE NEXT. 